Unable to get center text with span

```html
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
</head>
<body>
<p style="text-align:center;width:100%;">
  <span style="font-family:TheinhardtPan;">You have completed Day 1.</span>
</p>
</body>
</html>
```

inline styling `text-align:center`  not working for single line,
when add more than 2 line its starts working